MEXICO CITY — U.S. Secretary of State Hillary Rodham Clinton said today that America’s “insatiable” demand for illegal drugs and inability to stop weapons smuggling into Mexico are fueling an alarming spike in violence along the U.S.-Mexican border.

Clinton said the United States shares responsibility with Mexico for dealing with the violence. She said the administration will work with Mexican authorities to improve security on both sides of the border.

“Our insatiable demand for illegal drugs fuels the drug trade,” she said. “Our inability to prevent weapons from being illegally smuggled across the border to arm these criminals causes the deaths of police officers, soldiers and civilians.”

“I feel very strongly we have a co-responsibility,” she told reporters accompanying her to Mexico City a day after the Obama administration said it would send more money, technology and manpower to secure the United States’ Southwestern frontier and help Mexico battle the cartels.

Obama himself said Tuesday that he wanted the U.S. to do more to prevent guns and cash from illicit drug sales from flowing across the border into Mexico.

“That’s part of what’s financing their operations. That’s part of what’s arming them. That’s what makes them so dangerous,” he told a news conference. “And this is something that we take very seriously and we’re going to continue to work on diligently in the months to come.”

Clinton’s remarks, delivered ahead of her arrival in Mexico City, appeared more forceful in recognizing the U.S. share of the blame. Mexican officials have in the past, particularly under the Bush administration, complained that Washington never acknowledged the extent that the U.S. demand for drugs and weapons smuggling played in fueling the violence.

“These criminals are outgunning the law enforcement officials,” she said, referring to guns and military-style equipment like night vision goggles and body armor that the cartels are smuggling into Mexico from the United States.

“Clearly, what we have been doing has not worked and it is unfair for our incapacity … to be creating a situation where people are holding the Mexican government and people responsible,” Clinton said. “That’s not right.”

She said she would repeat her acknowledgment as loudly and as often as needed during her two-day visit to Mexico City and Monterrey during which she will brief Mexican officials on the administration’s plans for the border and counter-narcotics aid to Mexico.

The administration announced Tuesday that it would increase the number of immigrations and customs agents, drug agents and antigun-trafficking agents operating along the border. It will also send more U.S. officials to work inside Mexico.

In addition, it will allow federal funds to be used to pay for local law enforcement involved in Southwestern border operations and, at the same time, U.S. prosecutors will boost efforts to go after those smuggling guns and drug profits from the U.S. into Mexico.

The measures fall short of calls from some Southwestern states that troops be deployed to prevent further spillover of the violence, which has surged since Mexican President Felipe Calderon stepped up his government’s battle against the cartels.

“If the steps that we’ve taken do not get the job done, then we will do more,” Obama said.

In her discussions, Clinton plans to stress Obama’s commitment and encourage Calderon and his top aides to boost efforts to combat rampant corruption by promoting police and judicial reform, according to senior U.S. officials.

U.S. help for such projects has already begun under a three-year, $1.4-billion-dollar Bush administration-era program known as the Merida Initiative through which Congress already has approved $700 million to support Mexico’s efforts to fight the cartels.

Clinton’s visit is among several high-level meetings on the matter. Homeland Security Secretary Janet Napolitano and Attorney General Eric Holder are to meet with Mexican officials in early April before Obama is expected in Mexico ahead of the Summit of the Americas in Trinidad and Tobago.

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